The music-loving inhabitants of Pepperland are under siege by the Blue Meanies, a nasty group of music-hating creatures. The Lord Mayor of Pepperland dispatches sailor Old Fred to Liverpool, England, where he is to recruit the help of the Beatles (John Lennon, Paul McCartney, George Harrison, Ringo Starr). The sympathetic Beatles ride a yellow submarine to the occupied Pepperland, where the Blue Meanies have no chance against the Fab Four's groovy tunes.